Mast Rake for SF Bay

[Frank C]

Terry,

Raking the mast, like most things in life, is a compromise along a continuum. As noted elsewhere, reducing mast rake also reduces "weather helm" which is the boat's tendency to turn into the wind. Wxhelm is sailing's safety factor ... it forces you to hold the wheel slightly to prevent her turning to the wind. If you happen to get tossed overboard, slight weather-helm will cause the boat to head-up and stop, waiting for you like a well-trained horse!

On an average summer afternoon, central SF Bay provides a steady 15+ knots with moderate chop, gusts to 20+. I found that the standard 4 degrees of rake was unmanageable in those conditions (even with reefed main and jib, not Genoa). I had a new 5/32 forestay swaged at 4 inches shorter, which changed rake to exactly 2 degrees. I had earlier verified that my particular boat, as normally loaded, floats true to the bootstripe, and I just happened to own a digital carpenter's level. After using the trailer nose wheel to level the bootstripe, my carpenter's level showed the mast to be exactly 88 degrees with the new forestay. Even two degrees of rake in such conditions provides enough wxhelm to force a round-up if you're inattentive.

Though not usually noted, reduced mast rake INCREASES the boat's pointing angle, i.e. the factory rake would allow the boat to go closer to the wind, but then pull her onto the wind with slightest added gust. Therefore, after reducing rake you'll find her more steady in gusts, but also find her closest point to be further off the wind. You'll be happier sailing in SF Bay gusts, but you'll sail wider angles in mild conditions (about 50* in my case).

Another note ... when I made these changes, I was still new to sailing and new to the Mac. My novice assumption was that "full centerboard" was safer when sailing in heavy winds. However, the centerboard is a valuable asset in balancing the sailplan and controlling Wxhelm. After changes, I still sail with about 80% of centerboard down. However, before changing your mast rake, you can first try reduced sail and about 65% down-board.

Finally, adjusting mast rake alone will not solve all heavy air problems. To sail SF Bay successfully, you must adjust your sailplan and control the belly of the mainsail. The standard Mac rig won't be adequate. Overall, I'd recommend the following as priorities for sailing the 26X on San Francisco Bay:
1. Get the extra reef points in your mainsail (@ 25% & 50%).
2. Add Garhauer rigid vang to help flatten the mainsail.
3. Try twin mainsheets, also to help flatten the mainsail.
4. Add adjustable backstay, handy, not essential.
5. Reef the main at 25% before you go out.
6. Expect to use standard jib in summer winds, not Genoa.
7. Create drop measurement marks on your CB line.
8. Remember to experiment w/ centerboard adjustment when you tack.
9. If you're still frustrated by afternoon winds, shorten the forestay to reduce mast rake.

[Frank C]

Terry, I expect that Monterey Bay wind conditions are identical to San Francisco Bay. Beyond the wind, you have an ocean swell to contend with, and you have no Cityfront or island wind shadows to protect you.

Keep that centerboard free of kelp!

[Dimitri-2000X-Tampa]

Frank, did you have to lengthen the backstay also?

[Terry Chiccino]

Thanks for the tip Frank, I can see I've definitely got some experimenting to do here. I've currently got the mast rake set to the template the they give you in the owners manual. I'm hoping to have the boat in the water (Monterey Bay) on saturday, the weather reports look good with a chanch of rain on saturday night. We'll have to take a look at the swells with weather coming. I want to get some crab traps in the water and do some rock cod fishing. Once we get our fish then we can sail. I'll let you know! Thanks, Terry

[Frank C]

Dimitri, yes the factory backstay was too short. I cut the backstay off about 7' shorter, reswaged a loop and inserted a 4:1 tackle to create an adjustable backstay. I later split the backstay to attach to both port and starboard aft quarters. I also posted comments in answer to your other question under "Mast Backrake."

[HERNDON]

Frank:
Where do you launch from in Alameda?
I grew up on the base and are planning to sail
from there this summer.

Rob H.

[delevi]

Frank,

All good ideas. I've raked my mast close to vertical and reduced weather helm. It is also a good idea to really tighten the halyard & outhall. As Moe suggested, if you have a traveler, it works well to sheet it to winward and compensate by letting out some main sheet. This puts a lot of twist in the main sail and spills wind on top where it generates a lot fo heeling force. I also furl in some jib, about 1/3 along with reefed main when the winds get really nasty.

Leon

[Glenn C.]

Frank I have my rake at 1 degree and still have slight weatherhelm. She is very pleasent to control. But then there is Frank M.s theories. Heard from him lately Frank?

[Frank C]

Hello Glenn ... just joining, or just returning?

As mentioned at top of this very old thread, my mast is raked aft by exactly 2 degrees, determined with an electronic carpenter's level. The advantage of moving the mast forward (more erect than the factory-set rake of 4 degrees) is in reducing the boat's weatherhelm. Conversely, the (purported) disadvantage of reduced rake is that the boat will not point as close to the wind ... it seems to me that's correct too.

Frank M was always critical of changing the rake. He spends most of his forum time over on the Sailing Anarchy forum, but he also drops a post here once a month, or so. There's some recent scuttle that Frank's sailing prowess is notable - winner of recent races sponsored by BWY dealership?? Check-in & brag some, FM~!

[Richard O'Brien]

Conversely, the (purported) disadvantage of reduced rake is that the boat will not point as close to the wind ... it seems to me that's correct too.

Thanks Frank. I never realized that rake would have an effect on pointing? when I straightened my mast last year everything seemed better about it's performance except ability to point especially in winds under 6-7 kts. It was subtle, and i never put it together until you mentioned it. Now I think that I need an adjustable backstay for pointing in light air.

[Frank C]

Richard,

Yes, very subtle. I cannot guarantee that pointing effect is true, but I did read it on some now-forgotten dinghy racing website. It kinda makes sense, and maybe that explains why my tacks are 105 degrees apart!

[Glenn C.]

Hi Frank and all,
Yes Frank I am returning. I always hung out on the sailnet list. Some of your exchanges with Frank M. were real entertainment. On the subject of rake. It can be very difficult for some people (like myself) to get a handle on. I sail on the lakes of Mn. As with alot of lake sailing the winds are light, swirling and erratic. I generally have to tack every minute or two. Then, The winds may change or just die altogether. It makes it very hard to tell how you rig is performing. Point being, I read the posts and wonder what real sailing is like. You know, when you can set your sails and get 3 minutes (life time) on a run before tacking. Best I can tell my 1 degree gives me around 110 degrees to the wind. Thats in 6-7 kts. of wind. Closer if the winds pickup. Board and balance of coarse help. I have a 10 gal water tank under the V berth. That also has helped. Maybe the 2 1/2 hr. trek to Lake Superior would be worth it.